Is there a difference between book banning and book censorship?

Yes, a book can be censored without being banned. If a book is banned from a library, it will not be in the library selections at all. If a book is censored, it could be in the library, but certain words/phrases will be changed and/or omitted in order to make the book more "appropriate". For example, my school library houses "The Adventures of Huckleberry Finn", which is censored because the N word is replaced with a less offensive term so it does not offend anyone in the school who happens to read it.